Biodegradable Zn-1.5Cu-1.5Ag alloy with anti-aging ability and strain hardening behavior for cardiovascular stents
Biodegradable Zn-1.5Cu-1.5Ag alloy with anti-aging ability and strain hardening behavior for cardiovascular stents
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DOI：
10.1016/j.msec.2020.111172
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发表时间：
2020-11-01
影响因子：
7.9
通讯作者：
Yuan, Guangyin
中科院分区：
文献类型：
--
作者：
Chen, Chun;Yue, Rui;Yuan, Guangyin
锌及其合金由于其适中的降解速率和可接受的生物相容性而被认为是一类新的可生物降解金属。然而，不足的机械性能限制了它们的进一步应用，特别是用于心血管支架。本研究开发了一种具有优异力学性能的新型可生物降解的Zn-1.5Cu-1.5Ag（重量%）合金，并对其体外降解和细胞毒性进行了表征。显微组织表征表明，热挤压产生的晶粒尺寸和更细的第二相析出物的双峰分布。挤压态合金表现出令人满意的强度和塑性组合（屈服强度：162.0 +/-2.94MPa，极限拉伸强度：220.3 +/-1.70MPa和伸长率：44.13 +/- 1.09%）。在室温下老化8个月后，其力学性能提高约10%，具有良好的抗老化能力。由真应力-应变曲线计算出的应变硬化指数n表明该合金具有明显的应变硬化。在c-SBF溶液中的浸泡试验表明，该合金具有中等的腐蚀速率（48.6 +/- 4.14 μ m/年）和轻微的局部腐蚀行为。电化学测试表明，降解过程中表面形成了一层弱的钝化膜，其保护作用有限。细胞毒性试验表明，该合金具有可接受的体外生物相容性，与纯锌相当。根据力学性能、腐蚀行为和细胞毒性的结果，Zn-1.5Cu-1.5Ag合金可以被视为心血管支架应用的潜在候选者。
Zn and its alloys are considered as a new class of biodegradable metals due to their moderate degradation rates and acceptable biocompatibility. However, inadequate mechanical properties limit their further applications, especially for cardiovascular stents. In this study, a novel biodegradable Zn-1.5Cu-1.5Ag (wt%) alloy with excellent mechanical properties was developed, and then its in vitro degradation and cytotoxicity were characterized. Microstructural characterization showed that hot extrusion produced a bimodal distribution of grain size and much finer secondary phase precipitates. The as-extruded alloy exhibited a satisfactory combination of strength and plasticity (yield strength: 162.0 +/- 2.94 MPa, ultimate tensile strength: 220.3 +/- 1.70 MPa and elongation: 44.13 +/- 1.09%). After being aged at room temperature for 8 months, its mechanical properties increased about 10%, implying its good anti-aging ability. The strain hardening exponent (n) calculated from true stress-strain curve showed that this alloy has evident strain hardening. Immersion tests in c-SBF solution revealed that this alloy has a moderate corrosion rate (48.6 +/- 4.14 mu m/year) and slightly localized corrosion behavior. Electrochemical tests showed that a weak passive film formed on surface during degradation, which has a limited protective effect. The cytotoxicity tests exhibited that this alloy possesses acceptable in vitro biocompatibility, which is comparable to pure Zn. According to the results of mechanical properties, corrosion behavior and cytotoxicity, the Zn-1.5Cu-1.5Ag alloy can be regarded as a potential candidate for cardiovascular stent applications.